1. Field of the Invention
This invention relates to an arrangement of components for an engine, and particularly to an arrangement of a lubrication system, an intake system, an exhaust system and a cooling system for an outboard motor.
2. Description of Related Art
The air intake and exhaust systems of an engine can be arranged in a variety of ways. One of the most common arrangements is a cross-flow type in which the air intake system and the exhaust system are disposed on opposite sides of the engine. Another arrangement, which is not so common, is a counter-flow type in which, unlike the cross-flow type, the air intake system and the exhaust system are disposed on the same side of the engine.
There are several advantages to the counter-flow type engine. For example, because the air intake passage is positioned close to the exhaust passage, the intake air charge is warmed by the heat of the exhaust gasses. This expedites engine warm up, particularly during a cold conditions.
Another advantage of the counter-flow type of engine is that there is room on the side opposite the intake and exhaust systems for other engine components. Alternatively, this side of the engine can be placed closer to an inner wall of an engine compartment or a protective cowling.
A counter-flow type of engine includes a cylinder body that defines a cylinder bore or cylinder bores in which a piston or pistons reciprocate and a cylinder head affixed on an end of the cylinder body. The cylinder head, the pistons(s), and the cylinder bore(s) define a combustion chamber or combustion chambers. In general, part of the air intake system and the exhaust system are formed in the cylinder head. Because both of these systems are positioned on the same side of the engine, they occupy a relatively large space. This increases the size of the engine. A need therefor exists for an improved arrangement of the other engine components, and in particular, the lubrication system to make the counter-flow engine as compact as possible.
Outboard motors (counter or cross-flow types) typically include a vertically disposed crank chamber, which houses a vertically disposed crankshaft. Lubricant is supplied to the crank chamber by the lubrication system. Typically, lubricant is sprayed into the crank chamber and is deposited on the inner wall of the crank chamber because of the airflow generated by the circular motion of the crankshaft. The lubricant then flows down the sides of the crank chamber and collects at the bottom of the crank chamber. A return passage is usually provided at the bottom of the crank chamber. Lubricant flows through the return passage and is returned to an lubricant reservoir, which is usually located beneath the engine. A problem with this arrangement is that it typically takes a long time for the lubricant to travel down the sides of the crank chamber. Accordingly, a larger amount of lubricant is required in the lubrication system. A need therefore exists for a lubrication system that reduces the amount of time it takes for the lubricant to travel through the crank chamber.
Most outboard motors (counter or cross-flow types) are stored on their side with one side of the engine facing upward. While in this position, lubricant can accumulate in the crank chamber of the engine. The lubricant may then leak into the combustion chamber through the space between the cylinders and the piston. When the engine is started, this lubricant may cause poor emissions and retard ignition. It is, therefore, another object of the present invention to provide an improved lubrication system that prevents lubricant from accumulating in the crank chamber during storage.
It is well known that the lubricant in the lubricant reservoir must be periodically removed and changed. Accordingly, an lubricant drain for the lubricant reservoir is provided and is typically located near the center or rear side of the bottom surface of the lubricant reservoir. To add lubricant, an insertion port is also provided. Usually, the lubricant is drained from the reservoir by removing a plug of the lubricant drain. Alternatively, lubricant can be sucked out of the lubricant reservoir through a suction pipe that has been inserted into the insertion port. Typically, a problem with both of these methods is that old lubricant still remains in the bottom of the lubricant reservoir. A need therefore exists for an improved means for removing most or all of the lubricant from the lubricant reservoir.